There is an important need for improved screening and detection methods for cervical intra-epithelial neoplasia that are both sensitive and cost- effective. Recently, many groups have demonstrated that techniques based on quantitative optical spectroscopy have the potential to fulfill this need. Many optical techniques have shown promise for in vivo detection of pre-cancer including fluorescence spectroscopy, reflectance spectroscopy, multi-spectral fluorescence imaging, and multi-spectral reflectance imaging using polarized and unpolarized light. White it is clear than quantitative optical methods have the promise to deliver highly sensitive, specific and cost-effective screening and detection tools, the biological and morphological bases for the differences in optical spectra of normal and neoplastic cervic are not well understood. Moreover, the choice of illumination and detection wavelengths and geometries has been made arbitrarily on the basis of small in vitro studies. The specific goals of this proposal are five fold: (1) to conduct a series, , of studies to elucidate the biological and morphological basis for the difference between the fluorescence and reflectance spectra of normal and neoplastic cervical tissue in vivo, (2) to conduct a series of studies designed to explore how differences in the fluorescence and reflectance spectra of normal and neoplastic cervical tissues can be enhanced by using simple contrast agents such as acetic acid, toluidine blue, iodine and hyper- and hypo-tonic saline, (3) to develop analytic and computational models which describe tissue optical properties and measured spectra in terms of tissue biochemistry, morphology and architecture in the presence and absence of extrinsic contrast agents, (4) to use these models to predict which optical techniques, wavelengths, optical illumination and collection geometries and contrast agents will provide the best discrimination between normal and neoplastic cervical tissue, and (5) to develop inverse models which enable information about tissue biochemistry and architecture to be extracted from measured spectra to improve optical diagnostic algorithms for cervical pre-cancer. We believe that the proposed studies will yield important improvements in the sensitivity and cost-effectiveness of algorithms for detection of cervical pre-cancer based on optical spectra. In summary, the studies proposed here will develop a complete and quantitative understanding of the connections between tissue optical spectra and biochemistry, morphology and architecture.